Headrests are required on all vehicle seats to reduce the likelihood of severe head and neck injuries caused by rear end collisions. During a rear end collision, the occupant's head is thrown backwards at great force. Initially, upon impact, the occupant's torso moves forward as the vehicle is pushed forward, while the head lags behind. The head then rotates to the rear, bending or extending the neck backward in an extension-rotation motion. Then the head rebounds forward causing a flexed neck posture. The headrest on the vehicle seat is designed to limit the rearward rotation of the head and neck thereby reducing the risk of injury.
To minimize head and neck injury, the headrest must be positioned to engage the occupant's head during impact and prevent the head from being thrown backwards. Most vehicles are provided with an adjustment mechanism to enable the headrest to be selectively adjusted at the proper height. Unfortunately, many occupants find the headrest bothersome and lower the height of the headrest to its lowermost position where it provides little or no benefit.
Moreover, the adjustment mechanism must be sufficiently strong to withstand the impact from the head during a rear end collision without flexing, bending or collapsing to an extent such that the head and neck rotate too far rearward. During impact, the occupant's head typically is thrown rearwardly and rotates where it strikes the headrest in a downwardly inclined direction. In this manner, the impact force is generally rearwardly and downwardly rather than in a rearward direction only. Therefore, it is necessary to provide a headrest which will withstand the downward force of the head during impact in addition to withstanding the rearward force.
Although most automobile manufacturers provide some means for adjusting the height of the headrest, many of these adjusting mechanisms do not withstand the impact during a rear end collision. Presently, approximately two-thirds of the vehicles on the road today have head restraints that are rated very poor by the Insurance Institute for Highway Safety. Typically, almost 60% of all claims for insured accidents are a direct result of neck injuries from whiplash. Many of those injuries are caused by rear end collisions which can cause serious and lasting injuries at speeds as low as 12 miles per hour.
The data collected by the Insurance Institute for Highway Safety shows that many of the adjustment mechanisms on the head restraints do not adequately withstand the impact during a rear end collision. The head restraints often flex and pivot or rotate backwards upon impact which allows the head of the occupant to rotate rearwardly resulting in head and neck injuries. In addition, the adjustment mechanisms are shown to fail which allows the head restraint to retract or collapse to its lowermost position during impact. With the head restraint in its lowermost position, the restraint is not able to prevent the rearward neck rotation and, thus, is not able to prevent head and neck injuries.
Numerous devices have been proposed for providing suitable locking devices for vehicle headrests. An example for such a locking mechanism is disclosed in U.S. Pat. No. 3,544,162 to Uchiyamada. This device is intended to prevent the headrest from collapsing during rear end collisions, but is not adaptable to existing headrests. Accordingly, there Is a continuing need in the art for an improved vehicle headrest.